Fluorocarbon-type blowing agents which enable the easy formation of integral skin (IS) layers, especially chlorofluorocarbons (CFCs) represented by trichlorofluoromethane (Freon-11), are frequently employed as the blowing agents in conventional urethane foam molding materials for producing urethane steering wheels (ISF molded articles) because CFCs meet the requirements for blowing agents enabling easy formation of IS layers (i.e., having moderate boiling points (-40.degree. to 70.degree. C.) and being easily liquified by slight pressurizing) and are free from the fear of fire or explosion, non-toxic, and inexpensive. However, since fluorocarbons, particularly CFCs, are thought to be a cause of the destruction of the ozone layer, there is an international trend toward control of the use of these components. Hydrofluorocarbons (HCFCs), for this reason, are attracting attention because it is thought they are less apt to destroy the ozone layer. However, substitution of HCFCs is not the ultimate solution because the compounds are not thought to completely eliminate the fear of ozone layer destruction.
On the other hand, molded articles produced from PUR foam materials of so-called water-blown formulations in which water is employed as the blowing agent have been marketed. However, the water-blown formulations have conventionally been thought to be unsuited for the production of ISF molded articles because it has been difficult to form a uniform IS layer using such formulation. Illustratively stated, the water-blown formulation practiced by one skilled in the art, foaming is based on carbon dioxide gas generated by the reaction of an isocyanate with water and this carbon dioxide gas is less apt to liquify at ordinary mold temperatures. Even with pressurization, the carbon dioxide gas generated in the foaming system, in a mold, does not liquify nor does it liquify on the outer part of the mold, where temperatures are lower. As a result, an IS layer is hardly formed.